Rotational Moulding Polyamide 6 Composition for Stiffness and Cost
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Solution Overview
Problem
There is a need for alternative or improved polymer compositions for rotational moulding that can provide required physical properties at a relatively low cost, as existing polymers like polyethylene do not meet all application requirements, and more expensive alternatives like crosslinkable polyethylene or polycarbonate are often preferred for stiffness and resistance but are costly.
Innovation Solution
A polymer composition comprising at least 50.0 wt.% of polyamide 6, 5.0-40.0 wt.% of polyether block amide, and 0.25 to 5.0 wt.% of an additive package including light, heat, and/or UV stabilizers, antioxidants, rotational moulding processing aids, and lubricant/mould release agents, with a Melt Mass Flow Rate of 3.0 to 9.0 g/10 min @ 275°C and a moisture content of equal to or less than 0.20 wt.%, suitable for rotational moulding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyethylene is used for rotational moulding, then cost is reduced and processability is improved, but physical properties such as stiffness and chemical resistance are insufficient
Solution Approach 1:
The patent uses a blend of polyamide 6 and polyether block amide to create a composite material system. Polyamide 6 provides the required stiffness, strength, and chemical resistance, while polyether block amide contributes flexibility and impact resistance. This composite approach allows the material to achieve properties that neither polymer could provide alone, resolving the contradiction between processability and physical properties.
2Strength
If crosslinkable polyethylene or polycarbonate is used to improve stiffness and resistance, then physical properties are enhanced, but manufacturing cost increases
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific ratios of polyamide 6 (at least 50 wt.%) and polyether block amide (5-40 wt.%), along with optimized additive packages. This parameter optimization achieves the desired physical properties at a lower cost compared to using expensive polymers like polycarbonate or crosslinkable polyethylene, while still meeting performance requirements.
3Strength
If polyamide 6 is used to improve physical properties, then stiffness and strength are enhanced, but moisture content control becomes more critical
Solution Approach 1:
The patent introduces a comprehensive additive package that includes moisture scavengers, lubricants, and processing aids as intermediary substances. These additives mediate between the polyamide 6 and the processing environment, controlling moisture content during rotational moulding and preventing hydrolysis. The lubricants and processing aids facilitate proper flow and distribution while the moisture-scavenging components maintain reliability by keeping moisture content at or below 0.20 wt.%. cant
Solution Approach 2:
The patent optimizes the moisture content parameter to be at or below 0.20 wt.% through careful control of the additive package and processing conditions. This parameter control, combined with the specific polymer blend composition, ensures that the enhanced physical properties of polyamide 6 are achieved while maintaining reliability by preventing moisture-related degradation during processing and service.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polymer composition enhances impact properties, tensile properties, scratch resistance, and high-temperature operating capabilities while maintaining a low moisture content, making it suitable for a wide range of rotomoulded articles with improved physical properties at a lower cost.
Implementation Method 1
Once the melting temperature is achieved the material sticks to the wall of the mould in a layer to form the moulded part
Implementation Method 2
the arm holding the mould is moved to a cooling station where forced air, water mist or a combination of both is used to cool the mould to a temperature below the solidification point of the material
Data Source
Figure 1~2
Figure 3~4
AI summary
A polymer composition suitable for rotational moulding, a process for making the polymer composition, a process of manufacture an article from the polymer composition by rotational moulding, and a rotomoulded article formed from the polymer composition.